In the related art, treatments have been generally performed in which medical devices such as endoscopes and suction devices are introduced into a biological organ (for example, a body cavity such as an esophagus, airway, intestine, urinary duct, and other organs), and in which these devices are used so as to treat a lesion site appearing in the biological organ, or so as to perform removal of various foreign objects (capturing target) which are present inside the biological organ.
An example of the foreign object can include a calculus formed in the urinary tract. A urinary tract stone is the calculus, which is present in the urinary tract such as the kidney, urinary duct, bladder, and urethra. In case of a urolithiasis, various symptoms are caused to occur due to the urinary tract stone. For example, when the calculus formed inside the kidney moves to the urinary duct, the urinary duct is injured by the calculus, thereby causing pain or hematuria. The calculus occludes the urinary duct, thereby bringing a patient into a transient hydronephrosis state. Consequently, the patient is forced to feel a severe pain (colicky pain) in a range from the waist back to the flank. To remove the calculus is effective means for relieving or treating the symptoms.
In order to remove the calculus, a method has been widely used in which the calculus is picked and extracted by using basket forceps (refer to JP-T-2001-512355). However, it is necessary to pick the calculus one by one and to extract the calculus from a living body. Consequently, the method is a very laborious and inconvenient task.
Here, for example, if a method of collectively removing the calculus is tried in such a way that a filter for use in removing a foreign object inside the blood vessel or the like is diverted for the purpose of efficiently extracting the calculus, the above-described problem may be solved. However, it can be necessary to minimize the filter in view of the filter being introduced into a living body. Consequently, laborious work may be needed in both cleaning and replacement of the filer, thereby causing difficulties in sufficiently carrying out maintenance work.